The same but different: evidence for the co-evolution of language and toolmaking through neural re-use

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Useful abbreviations:

• AF = Arcuate Fasciculus
• SLF = Superior Longitudinal Fasciculus (SLF II/III)
• WM = white matter
• GM = gray matter
• L = left hemisphere
• R = right hemisphere
• AQ = Asymmetry Quotient
• PCA = Principal Component Analysis (PC_thin, PC_long - first two components of PCA)

Regions of interest: - PMv = ventral Premotor - BA44 = Brodmann Area 44 (pars opercularis) - BA45 = Brodmann Area 45 (pars triangularis) - STG = Superior Temporal Gyrus - MTG = Middle Temporal Gyrus - ITG = Inferior Temporal Gyrus - TP = Temporal pole - SPL = Superior Parietal Lobule - SMG = Supramarginal Gyrus - AG = Angular Gyrus

1 Data description and summary statistics

Table S1. Participant demographics.

				Fine motor experience			Gross motor experience
Participant	Gender	Age	Group	Craft	Years Exp	Ability	Craft	Years Exp	Ability	Education	Lithic Familiarity
1	M	32	exp	None	0	NA	None	0.0	NA	Masters	0
2	F	20	exp	Beading	1	1	None	0.0	NA	Undergraduate	0
3	F	26	exp	Crocheting	3	2	None	0.0	NA	Undergraduate	3
4	F	35	exp	Knitting	30	5	Carpentry	10.0	3	PhD	2
5	F	43	exp	Knitting	1	1	None	0.0	NA	Masters	0
6	M	44	exp	Painting	20	3	Carpentry	20.0	5	Masters	3
7	F	34	exp	Knitting	10	4	None	0.0	NA	Undergraduate	0
8	F	21	exp	Sewing	2	2	None	0.0	NA	Undergraduate	0
9	F	27	exp	None	0	NA	Carpentry	0.5	1	Masters	0
10	F	21	exp	Knitting	5	3	None	0.0	NA	Undergraduate	3
11	M	42	exp	Painting	11	3	Carpentry	16.0	3	Undergraduate	0
12	F	23	exp	None	0	NA	None	0.0	NA	Undergraduate	0
13	F	17	exp	Painting	8	3	None	0.0	NA	High school	1
14	M	48	exp	None	0	NA	Carpentry	35.0	3	Masters	0
15	F	30	exp	Painting	15	0	None	0.0	NA	Masters	3
16	M	46	exp	Painting	3	3	Carpentry	30.0	4	Undergraduate	1
17	F	28	exp	Sewing	5	1	None	0.0	NA	Undergraduate	3
18	F	42	exp	Sewing	11	3	None	0.0	NA	Masters	0
19	F	22	exp	None	0		None	0.0	NA	Masters	3
20	M	36	exp	Weaving	1	1	None	0.0	NA	High school	0
21	M	22	exp	None	0	NA	Sculpture/Pottery	7.0	0	Undergraduate	3
22	F	23	con	None	0	NA	None	0.0	NA	NA	NA
23	F	21	con	None	0	NA	None	0.0	NA	NA	NA
24	F	41	con	Beading	15	4	Carpentry	3.0	2	Masters	0
25	F	16	con	None	0	NA	Sculpture/Pottery	2.0	3	High school	0
26	F	23	con	None	0	NA	Pottery/Sculpture	2.0	2	NA	NA
27	F	19	con	Sewing	5	2	None	0.0	NA	Undergraduate	1
28	F	20	con	None	0	NA	None	0.0	NA	NA	NA
29	F	25	con	Knitting	1	1	None	0.0	NA	Undergraduate	0
30	F	25	con	Sewing	6	2	Carpentry	3.0	1	Undergraduate	0
31	F	37	con	Painting	21	5	Sculpture/Pottery	21.0	3	Undergraduate	0
32	M	29	con	None	0	NA	None	0.0	NA	Undergraduate	1
33	F	21	con	None	0	NA	None	0.0	NA	NA	NA
34	M	22	con	None	0	Na	None	0.0	NA	High school	1
35	F	35	con	Painting	7	3	None	0.0	NA	Masters	0
37	F	20	con	None	0	NA	None	0.0	NA	NA	NA
38	F	22	con	None	0	NA	None	0.0	NA	NA	NA
Note:
The skill with the greatest number of years of experience is show (and considered for analyses).

Table S2. A Descriptive statistics for behavioral measures (pre-training; all participants).

	n	mean	sd	se	min	max	range	skew
age	37	28.59	9.17	1.51	16.00	48.00	32.00	0.62
gross_motor_experience	37	4.04	8.81	1.45	0.00	35.00	35.00	2.23
fine_motor_experience	37	4.89	7.26	1.19	0.00	30.00	30.00	1.70
toolmaking_performance	26	1.91	0.51	0.10	1.10	2.93	1.83	0.15
PC_thin	30	-1.30	0.62	0.11	-2.32	0.20	2.52	0.40
PC_long	30	-0.13	0.40	0.07	-0.82	0.75	1.57	0.49
syntactic_complexity	26	1.00	0.57	0.11	-0.28	1.99	2.27	-0.22
AGL_d_grammaticality	26	0.62	0.66	0.13	-1.04	1.83	2.87	-0.42
AGL_d_chunk_strength	26	0.34	0.47	0.09	-0.49	1.15	1.64	-0.14
Note:
AGL = Artificial Grammar Learning, n = number of samples, SD = standard deviation, SE = standard error of the mean

Table S2. B Descriptive statistics for behavioral measures (post-training; exp group).

	n	mean	sd	se	min	max	range	skew
toolmaking_performance	13	3.24	0.64	0.18	1.63	3.84	2.21	-1.23
PC_thin	14	-0.87	0.61	0.16	-2.25	0.13	2.38	-0.44
PC_long	14	0.19	0.49	0.13	-0.36	0.96	1.32	0.38
syntactic_complexity	10	0.63	0.55	0.17	-0.18	1.72	1.90	0.38

2 Tractography results

2.1 Arcuate Fasciculus

2.1.1 Tractography result

2.1.2 White matter measures: average FA, WM tract volume

2.1.3 Gray matter measure: termination volume

2.1.4 Asymmetry Quotients

2.2 Superior Longitudinal Fasciculus (SLF II/III)

2.2.1 Tractography result

2.2.2 White matter measures: average FA, WM tract volume

2.2.3 Gray matter measure: termination volume

2.2.4 Asymmetry Quotients

3 Visualize correlation between behavioral variables

4 Lateralization of brain measures

Table S3 A. Asymmetry of AF and SLF II/III white matter tract measures.

		normality		significance test
Variable	n	W	p-value	Test	Statistic	p-value	BH q-value
AQ AF averageFA	37	0.944	0.062	t-test	1.247	0.221	0.294
AQ AF volumeWM	37	0.975	0.574	t-test	-2.175	0.036	0.072 *
AQ SLF averageFA	37	0.985	0.897	t-test	3.663	0.001	0.003 *
AQ SLF volumeWM	37	0.980	0.745	t-test	0.821	0.417	0.417

Table S3 B. Asymmetry of AF GM temrinations.

		normality		significance test
Variable	n	W	p-value	Test	Statistic	p-value	BH q-value
AQ AF PMv	37	0.980	0.742	t-test	0.790	0.435	0.608
AQ AF BA44	37	0.964	0.266	t-test	-1.608	0.117	0.272
AQ AF BA45	15	0.711	0.000	Wilcoxon signed-rank	60.000	1.000	1.000
AQ AF STG	35	0.782	0.000	Wilcoxon signed-rank	83.500	0.000	0.002 *
AQ AF MTG	37	0.982	0.784	t-test	-2.295	0.028	0.097 *
AQ AF ITG	37	0.973	0.502	t-test	1.001	0.324	0.567
AQ AF TP	13	0.737	0.001	Wilcoxon signed-rank	54.000	0.555	0.648

Table S3 C. Asymmetry of SLF II/III GM terminations.

		normality		significance test
Variable	n	W	p-value	Test	Statistic	p-value	BH q-value
AQ SLF PMv	37	0.988	0.947	t-test	0.971	0.338	0.406
AQ SLF BA44	37	0.963	0.258	t-test	-1.334	0.190	0.286
AQ SLF BA45	13	0.731	0.001	Wilcoxon signed-rank	60.000	0.091	0.183 *
AQ SLF SMG	37	0.960	0.201	t-test	-0.163	0.872	0.872
AQ SLF AG	37	0.831	0.000	Wilcoxon signed-rank	703.000	0.000	0.000 *
AQ SLF SPL	31	0.535	0.000	Wilcoxon signed-rank	413.000	0.001	0.002 *

5 Influence of prior experience on toolmaking performance (pre-training)

5.1 Effect of motor-skill experience

## 
## Call:
## lm(formula = toolmaking_performance ~ gross_motor_experience + 
##     fine_motor_experience, data = df)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.67574 -0.38784 -0.03171  0.39387  0.68611 
## 
## Coefficients:
##                         Estimate Std. Error t value Pr(>|t|)    
## (Intercept)             1.781716   0.111587  15.967 6.14e-14 ***
## gross_motor_experience  0.028957   0.009120   3.175  0.00422 ** 
## fine_motor_experience  -0.005978   0.014112  -0.424  0.67579    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.4414 on 23 degrees of freedom
## Multiple R-squared:  0.311,  Adjusted R-squared:  0.2511 
## F-statistic: 5.191 on 2 and 23 DF,  p-value: 0.01379

## Levene's Test for Homogeneity of Variance (center = median)
##       Df F value Pr(>F)
## group  1  2.8875 0.1022
##       24

## 
## Call:
## lm(formula = toolmaking_performance ~ group + gross_motor_experience, 
##     data = df)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.77719 -0.30431  0.06109  0.31506  0.63834 
## 
## Coefficients:
##                        Estimate Std. Error t value Pr(>|t|)    
## (Intercept)            1.570636   0.140997  11.139 9.61e-11 ***
## groupexp               0.306552   0.173558   1.766  0.09062 .  
## gross_motor_experience 0.025510   0.008302   3.073  0.00539 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.4158 on 23 degrees of freedom
## Multiple R-squared:  0.3886, Adjusted R-squared:  0.3354 
## F-statistic: 7.309 on 2 and 23 DF,  p-value: 0.003491

5.2 Effect of language measures

## 
## Call:
## lm(formula = toolmaking_performance ~ syntactic_complexity + 
##     AGL_d_grammaticality + AGL_d_chunk_strength, data = df)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -0.6001 -0.3535 -0.1072  0.2618  0.8938 
## 
## Coefficients:
##                      Estimate Std. Error t value Pr(>|t|)    
## (Intercept)           2.11819    0.26501   7.993 5.61e-07 ***
## syntactic_complexity -0.41173    0.22346  -1.842    0.084 .  
## AGL_d_grammaticality  0.05603    0.15884   0.353    0.729    
## AGL_d_chunk_strength  0.17093    0.24462   0.699    0.495    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.4689 on 16 degrees of freedom
## Multiple R-squared:  0.1799, Adjusted R-squared:  0.02608 
## F-statistic:  1.17 on 3 and 16 DF,  p-value: 0.3522

6 Pre-training partial correlations: toolmaking performance and brain measures

Table S4 A. Partial correlations between toolmaking performance and AQ of WM measures (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AQ AF averageFA	0.131	26	0.524	0.699
AQ AF volumeWM	0.056	26	0.784	0.784
AQ SLF averageFA	0.175	26	0.394	0.699
AQ SLF volumeWM	-0.366	26	0.066	0.262
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 B. Partial correlations between toolmaking performance and AQ of AF GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AQ AF PMv	0.418	26	0.033	0.117 *
AQ AF BA44	-0.438	26	0.025	0.117 *
AQ AF BA45	-0.541	10	0.106	0.248 *
AQ AF STG	-0.136	25	0.516	0.602
AQ AF MTG	-0.220	26	0.281	0.393
AQ AF ITG	-0.269	26	0.184	0.322
AQ AF TP	-0.187	7	0.689	0.689
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 C. Partial correlations between toolmaking performance and AQ of SLF II/III GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AQ SLF PMv	0.304	26	0.132	0.216 *
AQ SLF BA44	-0.408	26	0.039	0.216 *
AQ SLF BA45	-0.651	8	0.081	0.216 *
AQ SLF SMG	-0.121	26	0.556	0.585
AQ SLF AG	-0.295	26	0.144	0.216 *
AQ SLF SPL	-0.130	20	0.585	0.585
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 D. Partial correlations between toolmaking performance and WM measures (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AF L averageFA	0.158	26	0.440	0.560
AF R averageFA	0.270	26	0.182	0.486
AF L volumeWM	0.206	26	0.314	0.502
AF R volumeWM	0.142	26	0.490	0.560
SLF L averageFA	0.206	26	0.312	0.502
SLF R averageFA	0.378	26	0.057	0.228 *
SLF L volumeWM	0.392	26	0.048	0.228 *
SLF R volumeWM	-0.063	26	0.761	0.761
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 E. Partial correlations between toolmaking performance and AF left hemisphere GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AF L PMv	-0.270	26	0.183	0.320
AF L BA44	0.437	26	0.026	0.179 *
AF L BA45	0.718	5	0.172	0.320
AF L STG	-0.242	24	0.254	0.334
AF L MTG	0.320	26	0.110	0.320
AF L ITG	0.038	25	0.856	0.856
AF L TP	-0.598	5	0.286	0.334
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 F. Partial correlations between toolmaking performance and AF right hemisphere GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
AF R PMv	0.246	26	0.226	0.396
AF R BA44	-0.075	26	0.715	0.736
AF R BA45	0.836	5	0.078	0.273
AF R STG	-0.378	14	0.183	0.396
AF R MTG	0.069	26	0.736	0.736
AF R ITG	0.116	26	0.572	0.736
AF R TP	0.952	4	0.048	0.273
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 G. Partial correlations between toolmaking performance and SLF II/III left hemisphere GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
SLF L PMv	-0.077	26	0.707	0.707
SLF L BA44	0.332	26	0.097	0.146 *
SLF L BA45	1.000	3	0.000	0.000 *
SLF L SMG	0.459	26	0.018	0.055 *
SLF L AG	0.232	19	0.340	0.408
SLF L SPL	0.932	4	0.068	0.135 *
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S4 H. Partial correlations between toolmaking performance and SLF II/III right hemisphere GM terminations (controlling for gross motor experience).

Brain Measure	Partial r	n	p value	BH q value
SLF R PMv	0.223	26	0.273	0.674
SLF R BA44	-0.180	26	0.378	0.674
SLF R BA45	0.071	6	0.893	0.893
SLF R SMG	0.220	26	0.281	0.674
SLF R AG	0.155	26	0.449	0.674
SLF R SPL	0.078	19	0.752	0.893
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

7 Language aptitude (syntactic complexity) and brain correlations

Table S5 A. Correlation: language aptitude × AQ of WM measures

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AQ AF averageFA	-0.230	26	0.258	0.884
AQ AF volumeWM	0.156	26	0.447	0.884
AQ SLF averageFA	0.030	26	0.884	0.884
AQ SLF volumeWM	0.087	26	0.674	0.884
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 B. Correlation: language aptitude × AQ of AF GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AQ AF PMv	-0.114	26	0.579	0.579
AQ AF BA44	0.185	26	0.364	0.579
AQ AF BA45	0.333	9	0.381	0.579
AQ AF STG	0.134	24	0.533	0.579
AQ AF MTG	0.323	26	0.108	0.579
AQ AF ITG	0.132	26	0.520	0.579
AQ AF TP	-0.395	7	0.381	0.579
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 C. Correlation: language aptitude × AQ of SLF II/III GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AQ SLF PMv	-0.121	26	0.555	0.694
AQ SLF BA44	0.189	26	0.356	0.694
AQ SLF BA45	0.206	9	0.594	0.694
AQ SLF SMG	-0.289	26	0.151	0.640
AQ SLF AG	0.253	26	0.213	0.640
AQ SLF SPL	-0.091	21	0.694	0.694
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 D. Correlation: language aptitude × WM measures

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AF L averageFA	0.022	26	0.913	0.998
AF R averageFA	-0.171	26	0.403	0.998
AF L volumeWM	0.000	26	0.998	0.998
AF R volumeWM	0.104	26	0.614	0.998
SLF L averageFA	-0.091	26	0.660	0.998
SLF R averageFA	-0.071	26	0.730	0.998
SLF L volumeWM	-0.023	26	0.911	0.998
SLF R volumeWM	0.075	26	0.717	0.998
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 E. Correlation: language aptitude × AF left GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AF L PMv	0.137	26	0.504	0.846
AF L BA44	-0.107	26	0.604	0.846
AF L BA45	0.017	5	0.979	0.987
AF L STG	0.195	23	0.372	0.846
AF L MTG	0.003	26	0.987	0.987
AF L ITG	-0.468	24	0.021	0.127 *
AF L TP	-0.998	3	0.036	0.127 *
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 F. Correlation: language aptitude × AF right GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
AF R PMv	0.092	26	0.653	0.763
AF R BA44	0.145	26	0.481	0.763
AF R BA45	0.687	5	0.200	0.468
AF R STG	0.138	13	0.654	0.763
AF R MTG	0.321	26	0.110	0.468
AF R ITG	-0.039	26	0.851	0.851
AF R TP	0.692	5	0.195	0.468
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 G. Correlation: language aptitude × SLF II/III left GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
SLF L PMv	0.220	26	0.281	0.338
SLF L BA44	-0.250	26	0.219	0.328
SLF L BA45	-0.944	4	0.056	0.158 *
SLF L SMG	0.072	26	0.727	0.727
SLF L AG	-0.446	18	0.064	0.158 *
SLF L SPL	0.921	4	0.079	0.158 *
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S5 H. Correlation: language aptitude × SLF II/III right GM terminations

	Syntactic Complexity
Measure	Pearson’s r	n	p-value	BH q-value
SLF R PMv	0.065	26	0.753	0.753
SLF R BA44	-0.103	26	0.617	0.753
SLF R BA45	-0.527	7	0.224	0.448
SLF R SMG	-0.249	26	0.220	0.448
SLF R AG	0.080	26	0.696	0.753
SLF R SPL	-0.285	20	0.223	0.448
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

8 AGL scores (grammaticality and chunk strength) and brain correlations

Table S6 A. Correlation: AGL scores × AQ of WM measures

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ AF averageFA	-0.041	26	0.842	0.939	-0.097	26	0.639	0.939
AQ AF volumeWM	0.296	26	0.142	0.718	-0.189	26	0.355	0.939
AQ SLF averageFA	0.081	26	0.696	0.939	0.016	26	0.939	0.939
AQ SLF volumeWM	0.272	26	0.179	0.718	0.049	26	0.814	0.939
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 B. Correlation: AGL scores × AQ of AF GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ AF PMv	-0.139	26	0.497	0.869	0.278	26	0.169	0.592
AQ AF BA44	0.165	26	0.420	0.869	-0.358	26	0.072	0.506
AQ AF BA45	-0.058	10	0.874	0.941	-0.715	10	0.020	0.282
AQ AF STG	0.008	24	0.970	0.970	-0.300	24	0.154	0.592
AQ AF MTG	0.118	26	0.567	0.872	-0.143	26	0.487	0.869
AQ AF ITG	0.066	26	0.747	0.872	-0.074	26	0.720	0.872
AQ AF TP	0.136	9	0.728	0.872	-0.397	9	0.291	0.814
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 C. Correlation: AGL scores × AQ of SLF II/III GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ SLF PMv	-0.129	26	0.529	0.935	-0.006	26	0.977	0.979
AQ SLF BA44	0.156	26	0.446	0.935	-0.331	26	0.099	0.395
AQ SLF BA45	-0.325	7	0.477	0.935	0.162	7	0.728	0.970
AQ SLF SMG	0.005	26	0.979	0.979	-0.079	26	0.700	0.970
AQ SLF AG	-0.124	26	0.545	0.935	0.037	26	0.858	0.979
AQ SLF SPL	0.379	21	0.090	0.395	-0.455	21	0.038	0.395
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 D. Correlation: AGL scores × WM measures

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF L averageFA	0.074	26	0.720	0.994	0.183	26	0.370	0.988
AF R averageFA	0.025	26	0.905	0.994	0.064	26	0.755	0.994
AF L volumeWM	0.023	26	0.911	0.994	-0.143	26	0.487	0.994
AF R volumeWM	0.232	26	0.253	0.988	-0.205	26	0.316	0.988
SLF L averageFA	0.211	26	0.302	0.988	-0.007	26	0.974	0.994
SLF R averageFA	0.232	26	0.254	0.988	-0.002	26	0.994	0.994
SLF L volumeWM	-0.077	26	0.710	0.994	-0.128	26	0.535	0.994
SLF R volumeWM	0.204	26	0.317	0.988	-0.097	26	0.639	0.994
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 E. Correlation: AGL scores × AF left GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF L PMv	0.155	26	0.449	0.787	0.039	26	0.852	0.852
AF L BA44	-0.131	26	0.525	0.806	-0.075	26	0.717	0.828
AF L BA45	0.593	5	0.292	0.716	-0.340	5	0.576	0.806
AF L STG	-0.095	23	0.668	0.828	0.451	23	0.031	0.433
AF L MTG	0.060	26	0.769	0.828	0.269	26	0.183	0.716
AF L ITG	-0.196	25	0.347	0.716	-0.256	25	0.217	0.716
AF L TP	0.622	5	0.262	0.716	-0.530	5	0.358	0.716
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 F. Correlation: AGL scores × AF right GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF R PMv	0.059	26	0.774	0.897	0.247	26	0.224	0.776
AF R BA44	-0.022	26	0.914	0.914	-0.346	26	0.083	0.776
AF R BA45	0.282	6	0.588	0.776	-0.457	6	0.362	0.776
AF R STG	0.299	14	0.299	0.776	-0.190	14	0.514	0.776
AF R MTG	0.169	26	0.410	0.776	0.105	26	0.610	0.776
AF R ITG	-0.043	26	0.833	0.897	-0.310	26	0.124	0.776
AF R TP	0.601	6	0.207	0.776	-0.326	6	0.528	0.776
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 G. Correlation: AGL scores × SLF II/III left GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
SLF L PMv	0.155	26	0.450	0.961	0.025	26	0.904	0.961
SLF L BA44	-0.196	26	0.338	0.961	0.036	26	0.863	0.961
SLF L BA45	-0.763	3	0.447	0.961	1.000	3	0.012	0.139 *
SLF L SMG	0.128	26	0.533	0.961	-0.010	26	0.961	0.961
SLF L AG	0.244	19	0.315	0.961	0.014	19	0.954	0.961
SLF L SPL	0.220	5	0.722	0.961	-0.160	5	0.798	0.961
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S6 H. Correlation: AGL scores × SLF II/III right GM terminations

	AGL d’ grammaticality				AGL d’ chunk strength
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
SLF R PMv	0.004	26	0.984	0.994	0.085	26	0.680	0.994
SLF R BA44	-0.029	26	0.888	0.994	-0.305	26	0.130	0.780
SLF R BA45	-0.174	6	0.742	0.994	0.756	6	0.082	0.780
SLF R SMG	0.081	26	0.695	0.994	0.002	26	0.994	0.994
SLF R AG	0.005	26	0.981	0.994	-0.123	26	0.549	0.994
SLF R SPL	0.197	20	0.404	0.994	-0.280	20	0.231	0.925
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

# Mixed-design ANOVA for training effects

Table S7 A. Mixed design ANOVA for AQ WM measures.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AQ AF averageFA	0.001	0.973	0.000	1.773	0.196	0.038	3.873	26	0.061	0.080	0.243 *
AQ AF volumeWM	0.071	0.792	0.002	0.086	0.772	0.001	1.253	26	0.274	0.013	0.377
AQ SLF averageFA	1.286	0.268	0.032	3.917	0.059	0.060	0.890	26	0.355	0.014	0.377
AQ SLF volumeWM	0.347	0.561	0.011	0.014	0.907	0.000	0.812	26	0.377	0.007	0.377
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 B. Mixed design ANOVA for AQ of AF GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AQ AF PMv	0.066	0.799	0.002	1.420	0.245	0.025	0.306	26	0.585	0.006	0.683
AQ AF BA44	1.142	0.296	0.033	0.026	0.873	0.000	2.848	26	0.104	0.033	0.286
AQ AF BA45	0.226	0.659	0.045	0.088	0.782	0.004	1.763	6	0.255	0.067	0.446
AQ AF STG	2.329	0.141	0.074	0.652	0.428	0.007	4.235	24	0.052	0.044	0.286
AQ AF MTG	1.326	0.261	0.037	2.497	0.127	0.031	2.564	26	0.122	0.032	0.286
AQ AF ITG	1.614	0.216	0.039	1.670	0.209	0.027	0.120	26	0.732	0.002	0.732
AQ AF TP	0.162	0.726	0.065	1.000	0.423	0.065	1.000	4	0.423	0.065	0.592
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 C. Mixed design ANOVA for AQ of SLF II/III GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AQ SLF PMv	0.000	0.987	0.000	0.197	0.661	0.003	0.796	26	0.381	0.013	0.572
AQ SLF BA44	1.470	0.237	0.046	0.007	0.934	0.000	13.282	26	0.001	0.109	0.008 *
AQ SLF BA45	0.003	0.957	0.001	0.580	0.480	0.022	1.943	7	0.222	0.070	0.444
AQ SLF SMG	0.759	0.392	0.023	0.007	0.933	0.000	0.015	26	0.904	0.000	0.904
AQ SLF AG	3.209	0.086	0.058	3.201	0.086	0.067	2.086	26	0.162	0.045	0.444
AQ SLF SPL	0.446	0.514	0.018	0.029	0.866	0.001	0.123	18	0.730	0.003	0.876
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 D. Mixed design ANOVA for WM measures.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AF L averageFA	4.365	0.047	0.117	3.757	0.064	0.041	0.937	26	0.343	0.010	0.687
AF R averageFA	4.387	0.047	0.114	11.083	0.003	0.121	1.771	26	0.196	0.022	0.687
AF L volumeWM	0.088	0.769	0.003	0.023	0.880	0.000	0.287	26	0.597	0.002	0.796
AF R volumeWM	0.106	0.748	0.004	0.316	0.579	0.002	0.362	26	0.553	0.002	0.796
SLF L averageFA	1.634	0.213	0.053	0.716	0.406	0.005	2.482	26	0.128	0.018	0.687
SLF R averageFA	3.794	0.063	0.100	5.958	0.022	0.068	0.000	26	1.000	0.000	1.000
SLF L volumeWM	0.135	0.717	0.005	1.249	0.275	0.008	0.028	26	0.868	0.000	0.992
SLF R volumeWM	0.078	0.783	0.003	1.740	0.200	0.012	0.933	26	0.344	0.006	0.687
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 E. Mixed design ANOVA for AF left GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AF L PMv	2.623	0.118	0.082	0.346	0.562	0.003	0.112	26	0.741	0.001	0.802
AF L BA44	0.118	0.734	0.004	3.160	0.088	0.028	1.111	26	0.302	0.010	0.504
AF L BA45	NA	NA	NA	NA	NA	NA	NA	3	NA	NA	NA
AF L STG	0.107	0.747	0.004	0.664	0.424	0.008	4.990	23	0.037	0.057	0.183 *
AF L MTG	5.309	0.030	0.146	5.430	0.029	0.049	3.328	26	0.081	0.031	0.201 *
AF L ITG	0.510	0.482	0.013	5.522	0.028	0.087	0.064	25	0.802	0.001	0.802
AF L TP	NA	NA	NA	NA	NA	NA	NA	2	NA	NA	NA
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 F. Mixed design ANOVA for AF right GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
AF R PMv	1.785	0.194	0.049	3.988	0.057	0.049	0.097	26	0.758	0.001	0.977
AF R BA44	2.806	0.107	0.092	0.166	0.688	0.001	0.001	25	0.977	0.000	0.977
AF R BA45	1.265	0.378	0.385	0.077	0.808	0.000	17.308	4	0.053	0.065	0.319
AF R STG	0.148	0.709	0.010	1.889	0.203	0.075	0.605	11	0.457	0.025	0.977
AF R MTG	12.729	0.002	0.272	9.406	0.005	0.103	0.053	26	0.821	0.001	0.977
AF R ITG	0.320	0.577	0.007	2.813	0.108	0.059	0.025	24	0.875	0.001	0.977
AF R TP	NA	NA	NA	NA	NA	NA	NA	2	NA	NA	NA
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 G. Mixed design ANOVA for SLF II/III left GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
SLF L PMv	2.305	0.142	0.075	1.031	0.320	0.007	0.901	26	0.352	0.006	0.540
SLF L BA44	0.493	0.489	0.017	4.796	0.038	0.028	4.284	26	0.049	0.025	0.198 *
SLF L BA45	NA	NA	NA	NA	NA	NA	NA	2	NA	NA	NA
SLF L SMG	1.315	0.263	0.038	3.528	0.073	0.040	0.015	26	0.902	0.000	0.902
SLF L AG	0.760	0.396	0.030	0.500	0.490	0.011	0.733	18	0.405	0.016	0.540
SLF L SPL	NA	NA	NA	NA	NA	NA	NA	3	NA	NA	NA
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

Table S7 H. Mixed design ANOVA for SLF II/III right GM terminations.

	Effect: group			Effect: training			Effect: group × training
Variable	F	p-value	\(\eta G^2\)	F	p-value	\(\eta G^2\)	F	n	p-value	\(\eta G^2\)	adj p-value
SLF R PMv	3.708	0.066	0.093	2.648	0.117	0.035	0.357	26	0.556	0.005	0.936
SLF R BA44	5.920	0.023	0.162	0.054	0.818	0.000	3.216	26	0.086	0.028	0.513
SLF R BA45	0.620	0.475	0.106	1.170	0.340	0.065	0.090	6	0.780	0.005	0.936
SLF R SMG	0.642	0.431	0.016	2.328	0.140	0.037	0.001	26	0.977	0.000	0.977
SLF R AG	5.003	0.035	0.113	2.010	0.170	0.035	0.283	25	0.600	0.005	0.936
SLF R SPL	1.918	0.186	0.066	2.717	0.120	0.074	0.153	17	0.701	0.004	0.936
Note:
Asterisk (*) marks BH-adjusted p < 0.25.

8.1 Post-hoc analyses after ANOVA

9 Pre-post training changes in correlations

Table S8 A. Pre–post change in partial correlations (controlling gross motor experience) for AQ WM measures.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AQ AF averageFA	0.165	0.591	-0.017	0.956	-0.182	13	0.408	0.684	0.959
AQ AF volumeWM	-0.249	0.412	-0.232	0.446	0.017	13	-0.052	0.959	0.959
AQ SLF averageFA	0.180	0.557	0.119	0.698	-0.060	13	0.144	0.886	0.959
AQ SLF volumeWM	-0.183	0.549	-0.319	0.288	-0.136	13	0.421	0.674	0.959
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 B. Pre–post change in partial correlations (controlling gross motor experience) for AQ AF GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AQ AF PMv	0.073	0.812	-0.057	0.854	-0.130	13	0.294	0.769	0.769
AQ AF BA44	-0.411	0.163	-0.071	0.817	0.340	13	-0.930	0.352	0.444
AQ AF BA45	NA	NA	NA	NA	NA	3	NA	NA	NA
AQ AF STG	0.170	0.578	-0.261	0.390	-0.431	13	0.925	0.355	0.444
AQ AF MTG	-0.224	0.461	0.207	0.498	0.431	13	-1.092	0.275	0.444
AQ AF ITG	-0.804	0.001	0.082	0.789	0.886	13	-2.540	0.011	0.055 *
AQ AF TP	NA	NA	NA	NA	NA	2	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 C. Pre–post change in partial correlations (controlling gross motor experience) for AQ SLF II/III GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AQ SLF PMv	-0.003	0.993	0.036	0.906	0.039	13	-0.089	0.929	0.929
AQ SLF BA44	-0.165	0.591	0.133	0.666	0.297	13	-0.805	0.421	0.701
AQ SLF BA45	NA	NA	NA	NA	NA	2	NA	NA	NA
AQ SLF SMG	-0.076	0.806	0.501	0.081	0.576	13	-1.710	0.087	0.218 *
AQ SLF AG	-0.722	0.005	0.004	0.990	0.726	13	-2.143	0.032	0.161 *
AQ SLF SPL	-0.443	0.272	-0.294	0.480	0.149	8	-0.270	0.787	0.929
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 D. Pre–post change in partial correlations (controlling gross motor experience) for WM measures.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AF L averageFA	-0.049	0.872	0.397	0.180	0.446	13	-1.210	0.226	0.841
AF R averageFA	0.173	0.573	0.403	0.172	0.231	13	-0.555	0.579	0.879
AF L volumeWM	-0.349	0.243	0.103	0.737	0.452	13	-1.233	0.217	0.841
AF R volumeWM	-0.386	0.193	-0.092	0.764	0.293	13	-0.891	0.373	0.841
SLF L averageFA	0.185	0.545	0.448	0.124	0.263	13	-0.806	0.420	0.841
SLF R averageFA	0.462	0.112	0.404	0.171	-0.058	13	0.153	0.879	0.879
SLF L volumeWM	0.315	0.295	0.387	0.191	0.073	13	-0.229	0.819	0.879
SLF R volumeWM	0.092	0.764	-0.026	0.932	-0.119	13	0.327	0.744	0.879
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 E. Pre–post change in partial correlations (controlling gross motor experience) for AF left GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AF L PMv	-0.103	0.738	0.199	0.514	0.302	13	-0.848	0.396	0.819
AF L BA44	0.139	0.651	0.165	0.590	0.026	13	-0.068	0.946	0.946
AF L BA45	NA	NA	NA	NA	NA	1	NA	NA	NA
AF L STG	-0.489	0.090	-0.058	0.849	0.431	13	-1.418	0.156	0.781
AF L MTG	0.031	0.921	0.271	0.370	0.241	13	-0.688	0.492	0.819
AF L ITG	0.123	0.688	0.285	0.345	0.162	13	-0.368	0.713	0.891
AF L TP	NA	NA	NA	NA	NA	1	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 F. Pre–post change in partial correlations (controlling gross motor experience) for AF right GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
AF R PMv	-0.288	0.340	0.249	0.413	0.536	13	-1.519	0.129	0.178 *
AF R BA44	-0.291	0.334	0.429	0.144	0.720	13	-2.089	0.037	0.178 *
AF R BA45	NA	NA	NA	NA	NA	2	NA	NA	NA
AF R STG	-0.997	0.003	-0.839	0.161	0.158	4	-1.085	0.278	0.278
AF R MTG	-0.170	0.579	0.420	0.153	0.589	13	-1.628	0.103	0.178 *
AF R ITG	-0.508	0.111	0.216	0.524	0.723	11	-1.467	0.142	0.178 *
AF R TP	NA	NA	NA	NA	NA	1	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 G. Pre–post change in partial correlations (controlling gross motor experience) for SLF II/III left GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
SLF L PMv	0.077	0.802	0.310	0.302	0.233	13	-0.747	0.455	0.769
SLF L BA44	0.056	0.856	0.235	0.440	0.179	13	-0.491	0.623	0.769
SLF L BA45	NA	NA	NA	NA	NA	1	NA	NA	NA
SLF L SMG	0.520	0.069	0.427	0.146	-0.093	13	0.294	0.769	0.769
SLF L AG	0.523	0.121	-0.104	0.774	-0.627	10	1.471	0.141	0.565
SLF L SPL	NA	NA	NA	NA	NA	0	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S8 H. Pre–post change in partial correlations (controlling gross motor experience) for SLF II/III right GM terminations.

	Pre-training		Post-training		Change in association
Variable	Partial r (pre)	p-value (pre)	Partial r (post)	p-value (post)	Δr (post−pre)	n	Z (Steiger)	p-value (change)	BH q-value
SLF R PMv	-0.113	0.713	0.323	0.281	0.437	13	-1.162	0.245	0.306
SLF R BA44	-0.158	0.606	0.497	0.084	0.655	13	-1.926	0.054	0.270
SLF R BA45	NA	NA	NA	NA	NA	2	NA	NA	NA
SLF R SMG	0.135	0.661	0.599	0.031	0.464	13	-1.292	0.196	0.306
SLF R AG	-0.116	0.707	0.391	0.186	0.507	13	-1.170	0.242	0.306
SLF R SPL	0.414	0.308	0.728	0.041	0.314	8	-0.908	0.364	0.364
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

10 Handaxe morphology

10.1 Check if we need to control for gross-motor experience

Call: lm(formula = PC_thin ~ gross_motor_experience + fine_motor_experience, data = df)

Residuals: Min 1Q Median 3Q Max -0.97560 -0.46999 -0.04225 0.35614 1.56201

Coefficients: Estimate Std. Error t value Pr(>|t|)
(Intercept) -1.33192 0.14129 -9.427 4.96e-10 *** gross_motor_experience 0.02008 0.01256 1.599 0.122
fine_motor_experience -0.01292 0.01918 -0.674 0.506
— Signif. codes: 0 ‘’ 0.001 ’’ 0.01 ’’ 0.05 ‘.’ 0.1 ’ ’ 1

Residual standard error: 0.6153 on 27 degrees of freedom (7 observations deleted due to missingness) Multiple R-squared: 0.08746, Adjusted R-squared: 0.01986 F-statistic: 1.294 on 2 and 27 DF, p-value: 0.2907

Call: lm(formula = PC_long ~ gross_motor_experience + fine_motor_experience, data = df)

Residuals: Min 1Q Median 3Q Max -0.73849 -0.23490 -0.04482 0.19575 0.89252

Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) -0.138770 0.095346 -1.455 0.157 gross_motor_experience 0.003149 0.008474 0.372 0.713 fine_motor_experience -0.001013 0.012944 -0.078 0.938

Residual standard error: 0.4152 on 27 degrees of freedom (7 observations deleted due to missingness) Multiple R-squared: 0.005152, Adjusted R-squared: -0.06854 F-statistic: 0.06992 on 2 and 27 DF, p-value: 0.9326

10.2 run analysis

Table S9.A. Correlation: PCA components × AQ of WM measures (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ AF averageFA	-0.270	30	0.149	0.299	-0.499	30	0.005	0.040 *
AQ AF volumeWM	-0.024	30	0.902	0.992	0.202	30	0.285	0.394
AQ SLF averageFA	-0.197	30	0.296	0.394	-0.374	30	0.042	0.168 *
AQ SLF volumeWM	-0.276	30	0.140	0.299	0.002	30	0.992	0.992
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.B. Correlation: PCA components × AQ of AF GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ AF PMv	-0.040	30	0.834	0.896	-0.113	30	0.552	0.896
AQ AF BA44	-0.107	30	0.573	0.896	0.057	30	0.765	0.896
AQ AF BA45	0.085	12	0.793	0.896	-0.057	12	0.859	0.896
AQ AF STG	-0.046	28	0.816	0.896	0.061	28	0.759	0.896
AQ AF MTG	-0.042	30	0.827	0.896	0.126	30	0.508	0.896
AQ AF ITG	-0.135	30	0.476	0.896	0.025	30	0.896	0.896
AQ AF TP	0.528	9	0.144	0.896	0.136	9	0.728	0.896
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.C. Correlation: PCA components × AQ of SLF II/III GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AQ SLF PMv	-0.195	30	0.301	0.903	-0.039	30	0.840	0.953
AQ SLF BA44	0.028	30	0.883	0.953	0.031	30	0.872	0.953
AQ SLF BA45	-0.514	10	0.129	0.903	-0.424	10	0.222	0.903
AQ SLF SMG	-0.079	30	0.678	0.953	-0.063	30	0.740	0.953
AQ SLF AG	-0.064	30	0.735	0.953	-0.197	30	0.296	0.903
AQ SLF SPL	-0.013	24	0.953	0.953	-0.024	24	0.910	0.953
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.D. Correlation: PCA components × WM measures (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF L averageFA	0.079	30	0.679	0.724	0.300	30	0.108	0.301
AF R averageFA	-0.166	30	0.381	0.554	-0.168	30	0.375	0.554
AF L volumeWM	0.214	30	0.256	0.512	0.323	30	0.082	0.301
AF R volumeWM	0.098	30	0.606	0.693	0.381	30	0.038	0.301
SLF L averageFA	0.039	30	0.839	0.839	0.269	30	0.151	0.344
SLF R averageFA	-0.154	30	0.415	0.554	-0.131	30	0.492	0.605
SLF L volumeWM	0.428	30	0.018	0.293	0.295	30	0.113	0.301
SLF R volumeWM	0.193	30	0.306	0.544	0.334	30	0.072	0.301
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.E. Correlation: PCA components × AF left GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF L PMv	-0.228	30	0.226	0.894	-0.068	30	0.720	0.894
AF L BA44	0.231	30	0.220	0.894	0.131	30	0.489	0.894
AF L BA45	-0.014	7	0.976	0.976	0.108	7	0.817	0.894
AF L STG	-0.183	27	0.361	0.894	0.043	27	0.830	0.894
AF L MTG	0.098	30	0.607	0.894	0.153	30	0.419	0.894
AF L ITG	-0.088	28	0.656	0.894	-0.260	28	0.181	0.894
AF L TP	-0.345	5	0.569	0.894	-0.239	5	0.699	0.894
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.F. Correlation: PCA components × AF right GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
AF R PMv	-0.139	30	0.465	0.935	0.013	30	0.947	0.981
AF R BA44	0.112	30	0.556	0.935	0.288	30	0.123	0.935
AF R BA45	0.185	6	0.726	0.981	0.086	6	0.871	0.981
AF R STG	-0.360	16	0.170	0.935	-0.144	16	0.596	0.935
AF R MTG	-0.004	30	0.981	0.981	0.113	30	0.552	0.935
AF R ITG	-0.188	30	0.319	0.935	-0.099	30	0.601	0.935
AF R TP	-0.020	6	0.970	0.981	0.313	6	0.546	0.935
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.G. Correlation: PCA components × SLF II/III left GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
SLF L PMv	-0.077	30	0.684	0.978	-0.021	30	0.913	0.978
SLF L BA44	0.121	30	0.523	0.978	0.014	30	0.940	0.978
SLF L BA45	0.760	5	0.136	0.978	0.017	5	0.978	0.978
SLF L SMG	-0.031	30	0.871	0.978	-0.110	30	0.564	0.978
SLF L AG	0.027	22	0.906	0.978	0.078	22	0.729	0.978
SLF L SPL	-0.478	6	0.337	0.978	-0.247	6	0.638	0.978
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

Table S9.H. Correlation: PCA components × SLF II/III right GM terminations (PRE)

	PC thin (corss-sectional thinning)				PC long (elongation and pointedness)
Measure	Pearson’s r	n	p-value	BH q-value	Pearson’s r	n	p-value	BH q-value
SLF R PMv	-0.193	30	0.306	0.845	-0.053	30	0.779	0.942
SLF R BA44	0.152	30	0.423	0.845	0.115	30	0.544	0.863
SLF R BA45	-0.066	8	0.876	0.942	-0.465	8	0.246	0.845
SLF R SMG	-0.161	30	0.394	0.845	-0.169	30	0.371	0.845
SLF R AG	-0.014	30	0.942	0.942	0.107	30	0.575	0.863
SLF R SPL	-0.046	23	0.835	0.942	-0.186	23	0.396	0.845
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

11 Change in PCA-brain correlations

Table S10.A. Pre–post change: PCA components × AQ of WM measures (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AQ AF averageFA	-0.35	13	0.24	0.17	13	0.59	-1.19	0.23	0.64	-0.69	13	0.01	0.22	13	0.47	-2.35	0.02	0.04 *
AQ AF volumeWM	0.10	13	0.74	-0.03	13	0.93	0.33	0.74	0.74	0.60	13	0.03	-0.29	13	0.33	2.30	0.02	0.04 *
AQ SLF averageFA	-0.22	13	0.48	0.21	13	0.49	-1.00	0.32	0.64	-0.57	13	0.04	0.15	13	0.63	-1.76	0.08	0.11 *
AQ SLF volumeWM	-0.27	13	0.38	-0.06	13	0.84	-0.55	0.58	0.74	0.34	13	0.25	0.24	13	0.43	0.26	0.80	0.80
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_AQ_WM.png”

Table S10.B. Pre–post change: PCA components × AQ of AF GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AQ AF PMv	-0.28	13	0.36	0.02	13	0.94	-0.69	0.49	0.82	-0.62	13	0.02	-0.20	13	0.52	-1.17	0.24	0.40
AQ AF BA44	0.02	13	0.94	0.02	13	0.95	0.01	0.99	0.99	0.60	13	0.03	0.10	13	0.74	1.40	0.16	0.40
AQ AF BA45	NA	3	NA	NA	3	NA	NA	NA	NA	NA	3	NA	NA	3	NA	NA	NA	NA
AQ AF STG	0.18	13	0.56	-0.27	13	0.38	0.98	0.33	0.82	0.38	13	0.20	-0.35	13	0.25	1.70	0.09	0.40
AQ AF MTG	-0.08	13	0.78	-0.01	13	0.97	-0.17	0.86	0.99	0.32	13	0.29	0.28	13	0.35	0.10	0.92	0.92
AQ AF ITG	-0.04	13	0.89	0.33	13	0.28	-0.86	0.39	0.82	0.06	13	0.83	-0.28	13	0.35	0.77	0.44	0.55
AQ AF TP	NA	2	NA	NA	2	NA	NA	NA	NA	NA	2	NA	NA	2	NA	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_AQ_AF.png”

Table S10.C. Pre–post change: PCA components × AQ of SLF II/III GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AQ SLF PMv	-0.36	13	0.23	0.28	13	0.35	-1.53	0.13	0.63	-0.35	13	0.24	0.13	13	0.67	-1.11	0.27	0.90
AQ SLF BA44	0.06	13	0.83	-0.15	13	0.62	0.58	0.56	0.70	0.39	13	0.19	0.06	13	0.84	0.81	0.42	0.90
AQ SLF BA45	NA	2	NA	NA	2	NA	NA	NA	NA	NA	2	NA	NA	2	NA	NA	NA	NA
AQ SLF SMG	-0.09	13	0.78	0.13	13	0.68	-0.58	0.56	0.70	-0.04	13	0.90	0.13	13	0.67	-0.39	0.69	0.90
AQ SLF AG	-0.25	13	0.41	0.03	13	0.93	-0.67	0.50	0.70	-0.03	13	0.93	0.04	13	0.89	-0.17	0.87	0.90
AQ SLF SPL	-0.13	8	0.75	-0.33	8	0.42	0.29	0.77	0.77	0.05	8	0.91	0.13	8	0.75	-0.12	0.90	0.90
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_AQ_SLF.png”

Table S10.D. Pre–post change: PCA components × WM measures (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AF L averageFA	-0.16	13	0.59	0.24	13	0.42	-1.09	0.28	0.44	0.38	13	0.20	0.25	13	0.41	0.31	0.76	0.80
AF R averageFA	-0.61	13	0.03	0.40	13	0.18	-2.60	0.01	0.08 *	-0.51	13	0.07	0.45	13	0.12	-2.40	0.02	0.13 *
AF L volumeWM	-0.01	13	0.97	0.14	13	0.64	-0.43	0.67	0.76	0.18	13	0.55	0.07	13	0.83	0.29	0.77	0.80
AF R volumeWM	0.05	13	0.88	0.10	13	0.74	-0.16	0.87	0.87	0.53	13	0.06	-0.16	13	0.61	1.77	0.08	0.21 *
SLF L averageFA	-0.25	13	0.42	0.26	13	0.39	-1.45	0.15	0.39	0.24	13	0.44	0.34	13	0.25	-0.26	0.80	0.80
SLF R averageFA	-0.51	13	0.07	0.37	13	0.21	-2.07	0.04	0.15 *	-0.46	13	0.11	0.36	13	0.22	-1.99	0.05	0.19 *
SLF L volumeWM	0.59	13	0.03	0.17	13	0.57	1.28	0.20	0.40	0.08	13	0.81	-0.27	13	0.38	0.78	0.44	0.70
SLF R volumeWM	0.35	13	0.24	0.07	13	0.81	0.85	0.40	0.53	0.54	13	0.06	-0.02	13	0.94	1.46	0.15	0.29
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_WM.png”

Table S10.E. Pre–post change: PCA components × AF left GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AF L PMv	-0.48	13	0.10	-0.11	13	0.72	-1.19	0.23	0.39	0.21	13	0.49	0.15	13	0.63	0.15	0.88	0.92
AF L BA44	0.24	13	0.42	0.45	13	0.13	-0.58	0.56	0.56	-0.25	13	0.40	0.16	13	0.59	-0.99	0.32	0.81
AF L BA45	NA	1	NA	NA	1	NA	NA	NA	NA	NA	1	NA	NA	1	NA	NA	NA	NA
AF L STG	-0.41	13	0.17	0.03	13	0.94	-1.48	0.14	0.35	-0.05	13	0.86	-0.01	13	0.97	-0.10	0.92	0.92
AF L MTG	-0.12	13	0.70	0.44	13	0.14	-1.59	0.11	0.35	0.12	13	0.70	0.21	13	0.50	-0.21	0.84	0.92
AF L ITG	-0.24	13	0.43	0.11	13	0.73	-0.79	0.43	0.54	-0.28	13	0.36	0.29	13	0.34	-1.28	0.20	0.81
AF L TP	NA	1	NA	NA	1	NA	NA	NA	NA	NA	1	NA	NA	1	NA	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_AF_L.png”

Table S10.F. Pre–post change: PCA components × AF right GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
AF R PMv	-0.58	13	0.04	0.10	13	0.74	-2.07	0.04	0.19 *	-0.22	13	0.48	0.19	13	0.54	-0.96	0.34	0.42
AF R BA44	0.38	13	0.21	0.62	13	0.02	-0.95	0.34	0.43	0.69	13	0.01	0.16	13	0.60	1.63	0.10	0.41
AF R BA45	NA	2	NA	NA	2	NA	NA	NA	NA	NA	2	NA	NA	2	NA	NA	NA	NA
AF R STG	-0.79	4	0.21	-0.82	4	0.18	0.04	0.96	0.96	-0.05	4	0.95	-0.92	4	0.08	1.21	0.22	0.41
AF R MTG	-0.19	13	0.54	0.44	13	0.14	-1.72	0.09	0.22 *	0.31	13	0.30	0.45	13	0.12	-0.40	0.69	0.69
AF R ITG	-0.48	11	0.14	0.14	11	0.67	-1.25	0.21	0.35	-0.46	11	0.15	0.07	11	0.84	-1.16	0.24	0.41
AF R TP	NA	1	NA	NA	1	NA	NA	NA	NA	NA	1	NA	NA	1	NA	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_AF_R.png”

Table S10.G. Pre–post change: PCA components × SLF II/III left GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
SLF L PMv	-0.41	13	0.16	-0.06	13	0.83	-1.11	0.27	0.36	0.07	13	0.82	0.12	13	0.70	-0.11	0.91	0.91
SLF L BA44	0.15	13	0.62	0.58	13	0.04	-1.36	0.17	0.35	-0.29	13	0.34	0.36	13	0.23	-1.57	0.12	0.23 *
SLF L BA45	NA	1	NA	NA	1	NA	NA	NA	NA	NA	1	NA	NA	1	NA	NA	NA	NA
SLF L SMG	0.03	13	0.93	0.73	13	0.00	-2.15	0.03	0.13 *	-0.40	13	0.18	0.42	13	0.15	-1.91	0.06	0.22 *
SLF L AG	-0.22	10	0.54	0.00	10	1.00	-0.47	0.64	0.64	-0.25	10	0.49	-0.14	10	0.70	-0.23	0.82	0.91
SLF L SPL	NA	0	NA	NA	0	NA	NA	NA	NA	NA	0	NA	NA	0	NA	NA	NA	NA
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_SLF_L.png”

Table S10.H. Pre–post change: PCA components × SLF II/III right GM terminations (EXP)

	PC thin (cross-sectional thinning)									PC long (elongation and pointedness)
	pre-training			post-training			comparison			pre-training			post-training			comparison
variable	r	n	p	r	n	p	Z	p	BH q	r	n	p	r	n	p	Z	p	BH q
SLF R PMv	-0.64	13	0.02	0.18	13	0.55	-2.48	0.01	0.06 *	-0.28	13	0.35	0.30	13	0.31	-1.40	0.16	0.27
SLF R BA44	0.31	13	0.30	0.54	13	0.06	-0.78	0.44	0.44	0.36	13	0.22	0.35	13	0.25	0.04	0.97	0.97
SLF R BA45	NA	2	NA	NA	2	NA	NA	NA	NA	NA	2	NA	NA	2	NA	NA	NA	NA
SLF R SMG	-0.25	13	0.42	0.54	13	0.06	-1.95	0.05	0.13 *	-0.29	13	0.33	0.41	13	0.16	-1.67	0.10	0.24 *
SLF R AG	-0.35	13	0.24	0.39	13	0.18	-1.73	0.08	0.14 *	-0.08	13	0.79	0.25	13	0.41	-0.76	0.45	0.56
SLF R SPL	0.00	8	1.00	0.69	8	0.06	-1.41	0.16	0.20 *	-0.21	8	0.61	0.90	8	0.00	-2.77	0.01	0.03 *
Note:
Asterisk (*) marks BH-corrected results (q < 0.25).

[1] “figures/pre-post_toolmaking_PCA_SLF_R.png”

12 pre-post change in behavior